This invention relates to delivery of chemical agents to cells. More particularly, this invention relates to compositions and methods for intracellular delivery of chemical agents to a specific cell type, i.e. cells bearing the interleukin-2 (IL-2) receptor.
Toxins that target cell surface receptors or antigens on tumor cells have attracted considerable attention for treatment of cancer. E.g., I. Pastan & D. FitzGerald, Recombinant Toxins for Cancer Treatment, 254 Science 1173 (1991); Anderson et al., U.S. Pat. Nos. 5,169,933 and 5,135,736; Thorpe et al., U.S. Pat. No. 5,165,923; Jansen et al., U.S. Pat. No. 4,906,469; Frankel, U.S. Pat. No. 4,962,188; Uhr et al., U.S. Pat. No. 4,792,447; Masuho et al., U.S. Pat. Nos. 4,450,154 and 4,350,626. These agents include a cell-targeting moiety, such as a growth factor or an antigen-binding protein, linked to a plant or bacterial toxin. They kill cells by mechanisms different from conventional chemotherapy, thus potentially reducing or eliminating cross resistance to conventional chemotherapeutic agents.
Copending U.S. patent application Ser. No. 08/305,770, filed Sep. 13, 1994, describes compositions and methods for specific intracellular delivery of a chemical agent into a CR2-receptor-bearing cell, e.g. B lymphocytes. The compositions comprise a CR2-receptor-binding and endocytosis-inducing ligand (CBEL) coupled to the chemical agent. The CBEL binds to the CR2 receptor on the surface of B lymphocytes and elicits endocytosis of the composition such that the composition is transported to lysosomes. In the lysosomes, the chemical agent is preferably separated from the remainder of the composition such that the chemical agent can be transported or diffuse into the cytoplasm or nucleus. Optionally, the composition can include a spacer, which can be either biodegradable (in the lysosome) or non- biodegradable, for coupling the CBEL to the chemical agent. Chemical agents can include cytotoxins, transforming nucleic acids, gene regulators, labels, antigens, drugs, and the like. The composition can further comprise a carrier such as another water soluble polymer, liposome, or particulate.
Copending U.S. patent applications Ser. No. 08/616,693, filed Mar. 15, 1996, now abandoned, and Ser. No. 08/857,009, now abandoned, filed May 15, 1997, describe compositions and methods for specific intracellular delivery of a chemical agent into T lymphocytes. The compositions are represented by the formula [L--S].sub.a --C--[S--A].sub.b wherein L is a ligand configured for binding to a receptor on a T lymphocyte and stimulating receptor-mediated endocytosis of the composition, A is a chemical agent, S is a spacer moiety, C is a water soluble polymer having functional groups compatible with forming covalent bonds with the ligand, chemical agent, and spacer, and a and b are positive integers. These compositions are also designed to be transported to lysosomes, where the chemical agent is separated from the remainder of the composition for diffusion or transport to other locations in the cell. Preferred water soluble polymers include poly(ethylene glycol) and a copolymer of N-(2-hydroxypropyl)methacrylamide (HPMA). Preferred chemical agents include cytotoxins, transforming nucleic acids, gene regulators, labels, antigens, drugs, and the like. The composition can further comprise a carrier such as other water soluble polymers, liposomes, or particulates.
It would also be advantageous to develop additional compositions that are specifically targeted to other receptors on T lymphocytes. For example, targeting of T lymphocytes would enable therapeutic applications for T-cell-associated diseases and tissue graft rejection. Such T-cell-associated diseases include arthritis, T-cell lymphoma, skin cancers, psoriasis, multiple sclerosis, Type II diabetes mellitus, and diseases resulting from HIV infection.
In view of the foregoing, it will be appreciated that compositions for intracellular delivery of chemical agents to T cells and methods of use thereof would be significant advancements in the art.